Abstract: A method of transmitting a multi-carrier source signal, including symbols constituted by reserved carriers and data carriers. The method includes generating an additional signal that reduces peak-to-average power ratio of the signal to be transmitted. For each symbol, the method obtains M time samples representing the symbols and/or at least one iteration of: detecting P time samples from among P time samples representing the symbol, the P samples being the P samples of the highest amplitude among the M samples, or the P samples presenting a power value above a threshold; in the frequency domain, activating a reserved carrier, by addition of a pre-determined power to the reserved carrier; and for each activated reserved carrier: obtaining M time samples representing the activated reserved carrier, and applying a phase shift, taking account of the P detected samples, to the M time samples representing the activated reserved carrier.

Abstract: A method of transmitting a multi-carrier source signal, including symbols constituted by reserved carriers and data carriers. The method includes generating an additional signal that reduces peak-to-average power ratio of the signal to be transmitted. For each symbol, the method obtains M time samples representing the symbols and/or at least one iteration of: detecting P time samples from among P time samples representing the symbol, the P samples being the P samples of the highest amplitude among the M samples, or the P samples presenting a power value above a threshold; in the frequency domain, activating a reserved carrier, by addition of a pre-determined power to the reserved carrier; and for each activated reserved carrier: obtaining M time samples representing the activated reserved carrier, and applying a phase shift, taking account of the P detected samples, to the M time samples representing the activated reserved carrier.

Abstract: A method is provided for transmitting an information sequence from a source entity to a recipient entity, via at least one relay entity. The method includes: transmitting, by said source entity, modulated symbols representative of said information sequence, obtained after modulation of said information sequence, on a first channel, called ‘source’ modulated symbols; and transmitting, by said at least one relay entity, modulated symbols representative of said information sequence, obtained after modulation of an estimation of said information sequence on a second channel, called ‘relay’ modulated symbols, said first and second channels being orthogonal between each other. The source entity and the at least one relay entity simultaneously send at least one of said ‘source’ modulated symbols and at least one of said ‘relay’ modulated symbols.

Abstract: A method and apparatus for multicarrier transmission of a signal representing a source signal. The source signal includes symbols including a set of subcarriers, transmitted simultaneously and having pilot subcarriers intended for at least one processing operation for assisting and/or improving decoding in at least one receiver, and data subcarriers, the location in time-frequency space and a reference value of the pilot subcarriers being known to the at least one receiver. The method of transmission includes: a phase of modifying, for a given symbol, the reference value of at least one subset of the pilot subcarriers, by correction data configured to correct phase and/or amplitude for each of the pilot subcarriers of the subset, so as to minimize peak-to-average power ratio, the correction data taking at least three distinct values, a transition between the values of two successive pilot subcarriers of the subset on a frequency axis being constant.

Abstract: A method is provided for transmitting a digital signal via n transmit antennas, wherein n is strictly greater than 2. The method includes combining with a source data vector n vectors to be transmitted respectively by each of the transmit antennas by a coding matrix <I>M</I> with a yield equal to 1, using reference symbols known to at least one receiver whereby it is able to estimate at least three transmission channels corresponding respectively to each of the transmit antennas. The coding matrix <I>M</I> applies a mathematical transformation to the reference symbols prior to the transmission thereof.

Abstract: A method and apparatus for multicarrier transmission of a signal representing a source signal. The source signal includes symbols including a set of subcarriers, transmitted simultaneously and having pilot subcarriers intended for at least one processing operation for assisting and/or improving decoding in at least one receiver, and data subcarriers, the location in time-frequency space and a reference value of the pilot subcarriers being known to the at least one receiver. The method of transmission includes: a phase of modifying, for a given symbol, the reference value of at least one subset of the pilot subcarriers, by correction data configured to correct phase and/or amplitude for each of the pilot subcarriers of the subset, so as to minimise peak-to-average power ratio, the correction data taking at least three distinct values, a transition between the values of two successive pilot subcarriers of the subset on a frequency axis being constant.

Abstract: A method is provided for transmitting a digital signal via n transmit antennas, wherein n is strictly greater than 2. The method includes combining with a source data vector n vectors to be transmitted respectively by each of the transmit antennas by a coding matrix <I>M</I> with a yield equal to 1, using reference symbols known to at least one receiver whereby it is able to estimate at least three transmission channels corresponding respectively to each of the transmit antennas. The coding matrix <I>M</I> applies a mathematical transformation to the reference symbols prior to the transmission thereof.

Abstract: A method for transmitting a digital signal via n transmit antennas, wherein n is strictly greater than 2, comprising the steps of combining with a source data vector n vectors to be transmitted respectively by each of the transmit antennas by a coding matrix <I>M</I> with a yield equal to 1, using reference symbols known to at least one receiver whereby it is able to estimate at least three transmission channels corresponding respectively to each of said transmit antennas. Said coding matrix <I>M</I> applied a mathematical transformation to the reference symbols prior to the transmission thereof.

Abstract: The invention concerns a method for demodulating a digital signal received via a transmission channel, comprising a step which consists in associating with each value received of said received signal a point of the corresponding modulation constellation, on the basis of the decision boundaries taking into account the potential effect of a phase shift on at least one of said points of the modulation constellation and of the potential effect of an Gaussian additive noise applied on said point, said Gaussian additive noise being represented by a generating surface associated with said point, and said phase shift by a rotation on an angular range based so that said swept surface belongs essentially to the region of decision associated with the corresponding point of the modulation constellation, plotted on the basis of at least one phase and/or amplitude characteristic of said modulation, so as to associate with each of said points of the constellation a portion of a reception space, called corresponding region o

Abstract: A method for transmitting a digital signal via n transmit antennas, wherein n is strictly greater than 2, comprising the steps of combining with a source data vector n vectors to be transmitted respectively by each of the transmit antennas by a coding matrix <I>M</I> with a yield equal to 1, using reference symbols known to at least one receiver whereby it is able to estimate at least three transmission channels corresponding respectively to each of said transmit antennas. Said coding matrix <I>M</I> applied a mathematical transformation to the reference symbols prior to the transmission thereof.

Abstract: The invention concerns a method for receiving a signal using a multiple carrier and code division multiple access modulation, comprising a demodulating step by application of a mathematical transform of the temporal domain to the frequency domain, a step which consists in equalizing the transformed signal and a step which consists in despreading the equalized signal. The invention is characterised in that said equalizing step takes into account, for each of the components of said transformed signal, perturbations affecting the carrier bearing said component and at least one other of said carriers and at least some of said spread codes.

Abstract: The invention concerns a method for demodulating a digital signal received via a transmission channel, comprising a step which consists in associating with each value received of said received signal a point of the corresponding modulation constellation, on the basis of the decision boundaries taking into account the potential effect of a phase shift on at least one of said points of the modulation constellation and of the potential effect of an Gaussian additive noise applied on said point, said Gaussian additive noise being represented by a generating surface associated with said point, and said phase shift by a rotation on an angular range based so that said swept surface belongs essentially to the region of decision associated with the corresponding point of the modulation constellation, plotted on the basis of at least one phase and/or amplitude characteristic of said modulation, so as to associate with each of said points of the constellation a portion of a reception space, called corresponding region o

Abstract: A method for the time synchronization of a multi-carrier signal receiver consisting of a sequence of symbols each formed by a plurality of carrier frequencies. Each carrier frequency is modulated by a modulation coefficient. The position of some of said carrier frequencies in the time-frequency space is known to the receiver, and said frequencies are reference carrier frequencies. Each reference carrier frequency bears a reference coefficient with a value that is known to the receiver. The method includes a fine synchronization step, wherein the signal transmission channel impulse response is estimated on the basis of reference coefficients belonging to at least two received symbols. The beginning of the useful portion of each of the symbols is determined, and/or a receiver clock is controlled by analyzing the estimate of said impulse response.

Abstract: Decoding apparatus provides the maximum likelihood decoding of a sequence of samples of the type implementing a Viterbi type of decision algorithm that defines an initial decoding trellis. Sub-sampling apparatus sub-samples the initial trellis by a ratio p to preserve nodes corresponding to one sample out of p consecutive samples. This sub-sampling apparatus associates a p order antecedent node to each preserved node. Trace-back apparatus traces an optimal path back in the sub-sampled trellis by associating the p order antecedent node for each preserved node. The trace back apparatus designates at least the last two nodes of the optimal path. Over-sampling apparatus over-samples the designation of the last two nodes of the optimal path. The factor p is an integer greater than 1 selected so that there is a single path between a node and its p order antecedent in the initial trellis. Hence the bit rate is increased by a factor p, without loss of information.

Abstract: A method and apparatus for the coherent demodulation of a digital signal constituted by digital elements distributed in the time-frequency space and transmitted in the form of symbols constituted by a multiplex of N orthogonal carrier frequencies modulated by a set of said digital elements and broadcast simultaneously, the digital signal also including reference elements having a known value position in said time frequency space. The method includes a Fourier transform of at least samples of said digital signal containing said reference elements from a frequency domain into a temporal domain, a weighting of the transformed samples in the temporal domain by a rectangular temporal window f.sub.n, a thresholding of the transformed samples in the temporal domain to eliminate any samples below a predetermined threshold, and a reverse Fourier transform of the samples remaining after said weighting and thresholding from the temporal domain into the frequency domain for projection onto said digital signal.

Abstract: A method for the broadcasting of digital data, intended to be received notably by mobile receivers moving about in an urban environment, that is, under conditions of multiple propagation and in the presence of parasites and jamming, enabling a coherent demodulation under such conditions of reception. This method is one for the broadcasting of digital data, notably for radio broadcasting at a high bit rate towards mobile receivers, of the type providing for the distribution of the data in the form of digital elements in the frequency-time space f-t and the transmission of symbols each constituted by a multiplex of N orthogonal carrier frequencies modulated by a set of digital elements and broadcast simultaneously, certain of the digital elements being reference elements with a value and position in the frequency-time space f-t that are known to the receivers.

Abstract: A device for the transmission of digital data with at least two levels of protection, of the type providing for the distribution of the data to be transmitted in the form of digital elements in the time-frequency space and the transmission of symbols each formed by a multiplex of N orthogonal carriers modulated by a set of the digital elements, and transmitted simultaneously, the device including channel encoding means comprising at least two types of modulation and/or at least two encoding efficiency levels. This enables to optimize the use of the transmission channel by assigning differentiated transmission techniques to portions of data of a same digital train as a function of the different levels of protection sought, against transmission errors.

Abstract: A device for the transmission of digital data with at least two levels of protection, of the type providing for the distribution of the data to be transmitted in the form of digital elements in the time-frequency space and the transmission of symbols each formed by a multiplex of N orthogonal carriers modulated by a set of the digital elements, and transmitted simultaneously, the device including channel .[.encoding.]. .Iadd.encodes .Iaddend.means comprising at least two types of modulation and/or at least two encoding efficiency levels. This enables to optimize the use of the transmission channel by assigning differentiated transmission techniques to portions of data of a same digital train as a function of the different levels of protection sought, against transmission errors.